World-renowned keyboardist Jordan Rudess with Dream Theater plays the keyboard in front of his iPhone that he plays as a synthesizer using an app called Bebot. Aug 28, 2009

Photo: Lance Iversen, The Chronicle

World-renowned keyboardist Jordan Rudess with Dream Theater plays...

Image 2 of 3

World-reowned keyboardist Jordan Rudess with Dream Theater plays the synthesizer on his iPhone using the iPhone as a legitmate musical instrument and tool using an app called Bebot. Aug 28, 2009

Photo: Lance Iversen, The Chronicle

World-reowned keyboardist Jordan Rudess with Dream Theater plays...

Image 3 of 3

World-renowned keyboardist Jordan Rudess with Dream Theater plays the synthesizer on his iPhone using the iPhone as a legitimate musical instrument and tool using an app called Bebot at the Civic Auditorium Thursday Aug 27, 2009.

After progressive metal band Dream Theater finished its hard-charging second song at the San Jose Civic Auditorium, the lights dimmed and three large monitors above the stage flashed to keyboardist Jordan Rudess' fingers.

They began sliding over the screen of a small black device, difficult to identify from the audience. The sounds that emerged fell somewhere between a slide guitar and a theremin, that standard eerie accompaniment when UFOs appear in movies, the pitch gliding up and down with his digits.

What Rudess was playing before 1,500 fans was the iPod Touch. Specifically, his fingers were artfully manipulating the sounds of Normalware's Bebot application, which costs all of $1.99.

Among the tens of thousands of applications created for Apple Inc.'s iPod Touch and iPhone are more than 100 that transform the devices into music makers: synthesizers, guitars and drum machines that allow you to tap out rhythms and melodies, as well as trombones, flutes and ocarinas activated by blowing into the microphone.

Professional musicians are increasingly embracing the more sophisticated digital instruments, using them in live performances, DJ sets and recordings.

Attracted by the novelty

Many say they tinkered with the apps for the novelty and stuck around for the functionality: the different sounds, the unique interface or the simple convenience of being able to carry an instrument in your pocket.

The latter is key for San Francisco music producer and DJ Mark Farina, who in any given week could be spinning records for club kids in London, Istanbul or Tampa, Fla. That keeps him out of the studio for long stretches, and he can't exactly cart around the hefty old synthesizers and drum machines whose sound he favors.

Increasingly he's been using iPhone apps like TechnoBox and Bedrum, which closely approximate those vintage tones, as a scratch pad while he's stuck in airports or hotels.

"I can keep the same sort of analog units I like, play with them on the road and adapt them at home," he said.

But it's gone beyond that too. Farina liked a drum track he produced on the iPhone so much that the pattern and sounds ended up on a remix released earlier this year.

Similarly, Jay-J, a San Jose native who has produced remixes for Alicia Keys, Lil' Kim and Jill Scott, used the DigiDrummer app to create the shuffling high hats on the second track of his solo album, "Love Alive," which was released last month.

'Powerful tool'

He also regularly uses iPhone apps for testing levels in studios, tuning instruments and tapping out drum sounds over records when he works as a DJ.

"It's an incredibly powerful tool," he said.

Dream Theater's Rudess has played Bebot in front of audiences in Russia, Israel and Turkey, as well as on the solo section of "A Rite of Passage," on the band's newest album.

He's been a connoisseur of electronic instruments since his late teens, when he discovered the Minimoog, whose distinctive spacey sounds can be heard on classic songs by Herbie Hancock and more recent releases by Air.

The major advancement of the iPhone is the multi-touch screen, Rudess said. It opens up the possibility of sliding between notes and playing several at one time. It's more akin to a violin or cello than a keyboard or drum pad, the standard tools for electronic instruments and music software.

This is the very feature that Bebot exploits to produce its unique, sliding sounds.

"It makes the iPhone potentially one of the most versatile musical instruments, and it fits right in your pocket," said Russell Black, the Melbourne inventor of the product.

The hardware side of the electronic music industry is also dreaming up ways to expand on the potential of the iPhone, said Roger Linn of Berkeley, who developed the popular Linn lines of drum machines and guitar processors.

Some limitations

One possibility is building keyboards or stomp pedals with plug-in slots for iPhones. That would allow companies to rely on the processing power of the device as well as the Apple development tools that significantly reduce the time and cost of building software.

"The customer ultimately wins, because he is about to get more features to help his music for less money," Linn said.

Of course, there are limitations to the iPhone as an instrument. The most obvious is the 3 1/2-inch-wide screen, which makes it easy for fat fingers to strike wrong notes and limits the number of octaves accessible at one time. It is this shortcoming that ranks Rudess among those most anxious for Apple to release its long-rumored, much discussed tablet computer.

Meanwhile, as sophisticated as the touch screen is, it's still a far cry from the sensitive, weighted keys of high-end instruments that serious musicians use to create textured and nuanced harmonies and melodies.

Those who have invested decades building muscle memory on a keyboard don't necessarily want to start over on some newfangled interface, whatever its promise.

Limitless potential

"There are certainly people like Jordan (Rudess) who are always on the cutting edge and will take the time to do new and clever things with (the iPhone)," said Dave Smith, the St. Helena inventor of the Prophet-5 analog synthesizer. "The average person may not have the time to invest in a new way of playing."

He said he doubts the device will ever make the leap from a novelty embraced by a few pioneers to something used regularly by performing professionals.

Rudess, who consulted with Black on improvements to Bebot and worked with the Russian creators of a new music app called JR Hexatone Pro, disagrees.

He said that because developers around the world can easily build new applications for the iPhone, there's nearly limitless potential for new approaches to creating songs. Anticipated enhancements, like a larger screen and the ability to run multiple apps at once, will only expand the iPhone's use.

"That, to me, is the future of electronic musical instruments," he said.